August 16, 2014

1 - Venice hibiscus is a very pretty weed that may appear in your garden.

Yard and GardenAugust 16, 2014

Q.

I was directed to the NMSU Extension Service with a question I have about a plant in my garden. I have attached pictures of the plant. I am curious about what it is, but today my aunt warned that "leaves of three, leave them be" is an old saying and that identifying it might be important since we brush up against it while tending our garden.

My kids and I noticed today that the spent flowers from the bottom had opened back up and that they had seed pods inside. Very cool!

-Alexis K.

A.

Your aunt's warning "leaves of 3, let it be" is a caution often given to help people avoid poison ivy. Your plant is NOT poison ivy. There are many plants that have leaves composed of 3 leaflets, most are non-toxic, some are edible. However, if you do not know for sure which plant you are looking at, heed the warning and stay away from plants with leaves composed of 3 leaflets.

Your plant has leaves composed of 3 to 5 lobes, not leaflets. The pictures you sent were excellent and allowed me to identify your plant. I usually want to see the flowers, but you showed the seed pods which are opening to scatter their seeds. These pods identified the plant as a member of the mallow family. This family also includes cotton, okra, hibiscus, althea, and many other common garden plants. The other pictures showed the calyx (sepals) with pretty purple veins surrounding the seed pod, and sepals enclosing a closed pink flower. All together this clearly identified your plant as one known as Venice mallow, Hibiscus trionum. I found information about this plant in the book, Weeds of the West, by the Western Society of Weed Science and cosponsored by Cooperative Extension of the Landgrant Universities of the Western States. This book is in many libraries in New Mexico and other Western states. It is a very useful book and is available in bookstores and online if you wish to purchase a personal copy.

Your plant is indeed a weed, even though it is pretty and interesting. The problem is that it will produce numerous seeds and most of them will sprout in subsequent years and can become difficult to control and eliminate. It is an annual, so it will not come back from the roots next year. Prevention of seed development and dispersal is the best means of control. Since your pictures showed seed pods that have already opened, there is a real possibility that you will find more plants in your garden next year and perhaps for a few years into the future.

Even though your plant is related to common ornamental plants as well as to cotton and okra it is a weed. The others are beneficial plants while your plant can create problems. It is not native to the U.S. and was introduced from Europe.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

Links:

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.